Various devices, systems, and methods of locating conductors that are buried or otherwise obscured from sight are known in the art. For example, in some applications it is desirable to locate underground utilities which are conductors or have tracing conductors located adjacent to them by sensing magnetic fields emitted by the utilities. Examples of these are buried metallic pipes or conduits, as well as non-metallic pipes, such as gas or water lines, with associated trace wires or other conductors buried along with them. In these systems, a current signal may be coupled to the utility line using an external “buried utility transmitter” (also denoted herein as a “transmitter” for brevity), may be generated inherently from current flowing in the utility (e.g., by current flowing in a buried power cable or induced from a broadcast transmitter or power lines), or may be induced onto the conductor by other sources, such as from broadcast radio signals or utility power lines.
A separate locating device, also known as a “utility locator” (also denoted herein as a “locator” for brevity), may be used to detect magnetic field signals emitted from the utility and determine positional information, such as corresponding ground surface coordinates (above the utility), orientation, and/or depth, as well as other information such as underground structure or branching, other conductors in proximity to the targeted utility, ground characteristics, current flow in the utility, and the like.
Prior art locators are not ideal in situations where the transmitter cannot be easily connected to the utility or where the approximate location of the utility is unknown. For instance, in some installations a long stretch of buried pipe lacks an exposed surface portion or stub by which to physically couple a transmitter. An example is an open field where the pipe's approximate location is unknown.
In other types of devices, a single transmitter coil oriented orthogonal to and coplanar with a single sensing antenna coil may be used to produce a nulling effect at the sensing antenna coil based on the orientation of the transmitter coil to the sensing coil. When moved or when the associated environment around these devices change, distortions of the emitted signal may reduce the signal nulling, which can then be interpreted as indicating the presence of a conductor. However, systems utilizing such devices lack resolution and/or may fail to indicate orientation and/or depth of a detected utility line or other conductor, and may further result in falsely identifying a detected conductor as a targeted utility.
Accordingly, there is a need in the art to address the above-described as well as other problems.